Synthesis of Fe-Co based nanomagnetic materials

Processing of FeCo based nanomagnetic materials was carried out by chemical synthesis, crystallization from amorphous precursors and mechanical alloying. It was found that the products from chemical synthesis depended on the concentration of reaction solution. Uniform fiber like and spheroidal nanopowders were produced using Fe⁺² rich and Co⁺² rich reaction solutions respectively. The chemically synthesized FeCo based alloys was found to be amorphous. Through crystallization of melt spun amorphous precursors, high density nanocrystalline Fe_44.5Co _44.5Zr₇B₄ alloy was obtained; the nanocrystals had a compacted dendritic morphology. Spheroidal nanocrystalline structure was successfully obtained after mechanical milling of Fe_44.5 Co _44.5P₇B₄ for more than 20 h at 300 rpm. The fiber like and compact dendritic morphology was not suitable for soft magnetic properties. Due to the pinning of magnetic domains, the powder nanostructured FeCo based alloys had inferior soft magnetic properties to the ribbon form alloys. The fiber like chemically synthesized and mechanically alloyed FeCo based alloys powders showed large coercivities. The magnetization of chemically synthesized FeCo alloy powders was low, which was considered to be due to solid solution contaminations, amorphous phase formation and the oxidation layer.